1. Field of the Invention
The instant invention is related to the field of baths (such as in for example a swimming pool, a hot tub, a spa, a sauna, a whirlpool, a Jacuzzi, etc.) and maintenance and treatment of the water, associated facilities and equipment using antimicrobial agents, and the compounds therein.
2. Description of the Prior Art
A healthy and attractive pool should ideally contain crystal clear water that is free of any biological pathogens. The physical structures that are associated with a pool (such as the physical pool walls, drains and plumbing, pumps, deck, assorted instruments used to clean and maintain the pool, etc.) must also be free from biological pathogens as well. Traditional technology for treating and maintaining the quality of pool water is well known in the art and is described in, for example, Ralph L. Johnson, YMCA Pool Operations Manual, (Human Kinetics Publishers, Inc., Champaign, Ill., 1987), and David G. Thomas, Swimming Pool Operators Handbook, National Swimming Pool Foundation, Washington D. C., 1972).
Clarification of water in pools is usually accomplished via consecutive dilution using continuously flowing filtered water. While water that is turbid may be perfectly healthy for use, it is not usually attractive to most potential swimmers. Sand filters and diatomaceous earth filters employing both perpetual and temporary media have been the traditional choice for filtration of large commercial pools. Cartridge filtration, first developed for private pool use, has now been applied to larger pools as well. Because of the demands for high flow rate, it is impractical to attempt to filter out microscopic biological pathogens. Clarification is designed to remove larger particulate matter from suspension thereby reducing turbidity, and is generally not designed for removing biological pathogens. Biological pathogens are removed using antimicrobials. Commonly used antimicrobials for pools are chlorine, and the related halogens bromine and iodine. When chlorine gas is injected into pool water, the resulting chemical reaction produces hypochlorous acid, and hydrochloric acid. The hydrochloric acid, which is not a useful product and reduces pool pH, must be neutralized by the addition of soda ash. Hypochlorous acid is a strong bactericide and oxidizer, however it undergoes further ionization into hydrogen ion and hypochlorite ion, in a pH dependent fashion. Hypochlorite ion is not an effective bactericidal agent, and not a good oxidizer. Higher pH tends to increase the ionization of hydrochloric acid, and thus reduce the effectiveness of the bactericidal treatment. However, chlorine and related halogens are limited in the breadth and scope of antimicrobial action, and are limited to being present in solution with effective concentrations limited by concerns of the irritation and discomfort to swimmers by high concentrations.
The combination of warm water, high pH, and sunlight provide ideal conditions for algae (for example red, green, brown, black, or blue-black algae) to grow and become attached to the sides and bottoms of the pool. If uncontrolled, algae growth in an outdoor pool can spread very rapidly. While algae are generally not responsible for disease, it is desirable to eliminate them because they deplete chlorine, cause turbidity and slimy surfaces in and outside of the pool, and can cause foul odors which make the pool uninviting, and may also create safety hazards. Generally, preventive maintenance is seen as the best solution to algae problems. Usually the maintenance of a free chlorine residual above 1.0 ppm, and a pH range of 7.4 to 7.6 greatly reduces the chance of algae flowering, but it does not eliminate the problem. Prevention of algae growth is usually not difficult, but removing algae from a pool after it has gained a foothold can be extremely difficult, and normal procedures of treatment with halides are ineffective.
Standard treatments are inefficient in stopping the establishment of algae, at lower concentrations that are not irritating to swimmers, and are generally directed to inhibiting the flowering of algae. The most effective and practical method of treatment once the algae have attached, is to drain the pool and physically clean the growth off with a dilute muriatic acid or hypochlorite solution. It would be very useful to have new disinfecting agents for pools that could be used to effectively inhibit algae growth and/or eliminate bacteria in pools, that is both easy to use and will have a minimal impact on the delicate balance of water quality in the pool. Highly effective, non-toxic antimicrobial agents which could inhibit the growth of bacteria, fungi, and yeast, especially on surfaces would be highly desireable.
Most preventative measures attempt to limit the growth of algae by treating water. The earliest algicide to be used extensively in natural waters was copper sulfate, but the toxicity makes them inappropriate for use in pools. High concentrations can cause skin rashes and turn hair green, and may cause a milky precipitate to form in highly alkaline or sulfur containing water. Some mercury compounds (phenylmercuric acid) have been found to be algaecidal, and were previously used, but the cumulative toxicity has ruled out its further use in pools. Quaternary ammonia compounds (QACs), most commonly quaternary ammonia halides, are more effective than copper and not as toxic. Unfortunately, when these compounds react with chlorine, chloramines may be formed which cause eye irritation. QACs will also reduce chlorine levels, increase chlorine demand, collect on filters, and cause pool water to foam, thus having negative effects on water chemistry and clarity. Unfortunately, it has been noted that some algae have developed resistance to QACs.
Linear polymeric biguanides have been disclosed in British Patent 1,407,258 to control the growth of algae and bacteria in swimming pool water. Additionally, British Patent 1,464,005 uses a linear polymeric biguanide as a water treatment for the destruction of aquatic molluscs. The preferred polymeric biguanide for use in both inventions is poly(hexamethylene biguanide) in the form of its hydrochloride salt.
Substituted and branched alkylamines, as in for example, U.S. Pat. No. 4,608,289, and N,N-Dimethylalklamine oxides, for example as discussed by Devinsky et al., (1990, J. Pharm. Pharmacol. 42: 790-794) have been studied for their antimicrobial properties. These substituted and branched alkylamines when incorporated into liquid or molten plastic materials provide fungicidal and bactericidal properties. Examples of plastic materials cited in U.S. Pat. No. 4,608,289 are polyvinyl chloride (PVC), polyethylene, cellulose acetate buterate, polyolefins, polypropylenes, polystyrene, various phenolic resins and polystyrene butadiene.
This invention provides for compounds which are suitable for general use in the treatment of swimming pools, spas, etc and is especially concerned with the treatment of surfaces which tend to become fouled by microorganisms. The addition of this invention to an aquatic environment prevents surface adherence to materials commordy used in swimming pools, spas and the like while keeping the water appearance fresh and clean.